In the related art, an imaging apparatus for diagnosis has been widely used in order to perform diagnosis on arteriosclerosis, to perform preoperative diagnosis when endovascular therapy is performed by using a high-function catheter such as a balloon catheter or a stent, or to verify results after surgery.
The imaging apparatus for diagnosis includes an intravascular ultrasound (IVUS) device, an optical coherence tomography (OCT) device, and the like. The imaging apparatus for diagnosis is used to generate a tomographic image inside a blood vessel. In this manner, it is possible to perform anatomical diagnosis inside the blood vessel.
In recent years, it has been discovered that a therapeutic outcome is improved by using a physiological technique (method for evaluating presence or absence of actual ischemia or a degree of the ischemia) in addition to the above-described anatomical technique, as an intravascular diagnosis technique.
However, in order to perform intravascular diagnosis by using the physiological technique, it is necessary to use load echocardiography, stress electrocardiography, or stress myocardial scintigraphy. In general, it is difficult to use these devices concurrently with the anatomical technique.
In particular, during an emergency, or in a case of percutaneous coronary intervention, it becomes more difficult to perform these procedures concurrently with the anatomical technique.
On the other hand, in recent years, as an evaluation parameter in the physiological technique, a myocardial fractional flow reserve (FFR) has been focused on.
The myocardial fractional flow reserve is an indicator which indicates that blood flow flowing in a situation where a stenotic lesion is absent when a coronary artery is dilated to the maximum (during maximum coronary artery dilation) becomes a hindrance to some degree for the stenotic lesion. The myocardial fractional flow reserve can be calculated by measuring pressure at a proximal stenosis site and a pressure at a distal stenosis site during the maximum coronary artery dilation.
Therefore, it is possible to perform the physiological technique by arranging a pressure sensor inside a probe unit and measuring the pressures (for example, see Japanese Patent Application Publication No. 2003-525067, Japanese Patent Application Publication No. 2007-296354, Japanese Patent Application Publication No. 2012-501807, and Japanese Patent Application Publication No. 2012-502773. Also see, Takashi Akasaka: “Application of a Pressure Guide Wire with Thermography in the Assessment of Coronary Stenotic Lesions”, Medical and Biological Engineering 43(1): 24-31, 2005).
Furthermore, if the pressure sensor is arranged inside a probe unit of the imaging apparatus for diagnosis so as to be compatible with a transmitting and receiving unit for generating a tomographic image, it is considered that a combined use of the anatomical technique and the physiological technique can be realized.